Magnetic disk apparatuses such as a hard disk drive (HDD) have employed a CSS (Contact Start and Stop) system in which a magnetic head is held in contact with a contact sliding region (CSS region) provided in an inner peripheral region on the surface of a magnetic disk while the apparatus is stopped, then at the time of start-up, the magnetic head is flown up while sliding in contact with the disk surface in the CSS region and then recording/reproduction is carried out on the surface of a recording/reproducing disk region provided outside the CSS region. In a finishing operation, the magnetic head is retreated from the recording/reproducing region to the CSS region and then is landed while sliding in contact with the disk surface in the CSS region so as to be stopped. In the CSS system, the start-up operation and the finishing operation where the contact sliding occurs are called CSS operations.
In such a CSS-system magnetic disk, it is necessary to provide both the CSS region and the recording/reproducing region on the disk surface. Further, in order to prevent adsorption between the magnetic head and the magnetic disk while they are in contact with each other, it is necessary to provide a convex-concave shape having a certain surface roughness on the surface of the magnetic disk.
In order to suppress damage due to the contact sliding between the magnetic head and the magnetic disk during the CSS operations, there is known a magnetic recording medium or the like coated with a perfluoroalkylpolyether lubricant having a structure of HOCH2—CF2O—(C2F4O)p—(CF2O)q—CH2OH according to Japanese Unexamined Patent Application Publication (JP-A) No. S62-66417 (Patent Document 1) or the like, for example.
Further, Japanese Unexamined Patent Application Publication (JP-A) No. 2000-311332 (Patent Document 2) discloses a magnetic recording medium coated with a lubricant in a combination of a cyclic triphosphazene-based lubricant and a perfluoropolyether-based lubricant, that can improve the lubricating properties and the CSS properties without decomposing the lubricant even when a low-flying magnetic head is used. Further, Japanese Unexamined Patent Application Publication (JP-A) No. 2004-152460 (Patent Document 3) discloses a magnetic disk with a highly adhesive lubricating layer that can stably operate even in the case of a very low flying height and that can suppress migration, using a lubricant in a combination of a perfluoropolyether compound having a phosphazene ring as a terminal group and a perfluoropolyether compound having a hydroxyl group as a terminal group.    Patent Document 1: Japanese Unexamined Patent Application Publication (JP-A) No. S62-66417    Patent Document 2: Japanese Unexamined Patent Application Publication (JP-A) No. 2000-311332    Patent Document 3: Japanese Unexamined Patent Application Publication (JP-A) No. 2004-152460